1. Technical Field
The present invention relates to a semiconductor package, and more especially, to a package structure for DC-DC converter capable of encapsulating multiple elements including chips in a package.
2. Description of Related Art
In a DC-DC converter, there are usually two MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistor) used as switches. FIG. 1 shows a circuitry of DC-DC converter comprising two connected N-type MOSFETs. wherein a gate electrode G1 of a high-side MOSFET and a gate electrode G2 of a low-side MOSFET both connect to a controller; a drain electrode D1 of the high-side MOSFET (HS) connects to a Vin end, a source electrode S1 connects to a drain electrode D2 of the low-side MOSFET (LS), and a source electrode S2 of the low-side MOSFET connects to a Gnd end, composing the DC-DC converter. Usually parts including capacitor and inductor are set between the Vin end and Gnd end of the DC-DC converter.
As shown in FIG. 2, a DC-DC converter package encapsulates a high-side MOSFET chip, a low-side MOSFET chip and a controller in one package, reducing the number of component count and improving the efficiency of the power supply.
However, for an actual package, the said high-side MOSFET chip, low-side MOSFET chip, and controller are set parallel on a same plane of the lead frame, therefore the installation space of the package limits the size of the high-side MOSFET chip, the low-side MOSFET chip and the controller chip to a large extent, which greatly limits the performance improvement of the DC-DC converter.